The isomerization of organic compounds having double bonds has been of interest to chemists and there are many methods available such as the isomerization in the presence of acids providing protons like sulfuric acid. However, isomerizations involving acids like sulfuric acid are not specific and is hard to predict where the double bond will end up and what kind of an equilibrium mixture of all the possible isomers will be obtained.
Replacing specific C-H bonds with C-D bonds has enabled chemists to understand reaction mechanism by measuring primary and secondary kinetic isotope effects. Biologists and biochemists have used deuteration techniques to follow the fate of specific hydrogens on a molecule in biological processes. Most deuteration procedures are involved and expensive. A simple procedure for regioselective deuteration using a cheap deuterium source such as D.sub.2 O is attractive. Olefins are important starting compounds for organic synthesis. A procedure for regioselective deuteration of olefins with D.sub.2 O is very desirable for producing deuterated compounds.
Sulfur dioxide has been employed for the isomerization of olefins and this has been disclosed in a British patent to Colgate-Palmolive Peet Company No. 532,685 accepted on Jan. 29, 1941. In particular, this patent is concerned with the alkylation of aromatic rings by reaction with alkyl halides or olefins and the acylation of aromatic compounds by reaction with carboxylic acid halides or carboxylic acids and with the polymerization, isomerization and condensation and cyclization of hydrocarbons and their derivatives, including saturated and unsaturated aliphatic cyclic, alicyclic, aromatic and substituted aromatic hydrocarbons and many of their derivatives. The isomerization of normal pentene gives isoamylene and amylene and 3-methyl-butene-1.
J. H. Deboer in Koninklijke Nederlandse Academie Wetenschappen Proc. Vol. 50, page 1181 [1947] discloses a mechanism of isomerizations of unsaturated fatty acids by SO.sub.2. This application is mostly concerned with cis-trans isomerization and catalyzed conjugation. However, it does not relate to isomerization of double bonds at tertiary carbon atoms.
A Keuzenkamp in the Journal of the American Oil Chemists Society, page 479, issued Sept. 1949, describes the catalytic isomerization of cod liver oil with sulfur dioxide. The disclosure does not relate to isomerization at tertiary carbon atoms.
H. I. Waterman in Research Supplement 2-12, page 583, issued 1949, describes the isomerization of olefinic double bonds by sulfur dioxide. This application describes the shifting of double bonds in the presence of sulfur dioxide but does not mention isomerization involving tertiary carbon atoms.
F. Vohwinkel in Farbe und Lack, Vol. 65, page 571 [1959] reviews the effect of sulfur dioxide on vegetable oils, for catalyzing the shifting of isolated double bonds to conjugated double bonds, the cis-trans isomerization and the polymerization. He does not mention any effects relating to the isomerization involving teritary carbon atoms.
Walter E. Rathjen et al. in U.S. Pat. No. 3,278,567 discloses a process for conjugating and isomerizing drying oils and products with sulfur dioxide at temperatures between 475.degree. F. and below 550.degree. F. He finds that cis-trans isomerization occurs for the drying oils but does not report any effects on tertiary olefinic carbon atoms.
A. W. Hudgell et al. in J. Chem. Soc. 1954, 814-16 discloses the isomerization of diene and triene steroids in sulfur dioxide to identified and unidentified products at reaction temperatures between 20.degree. C. and predominantly 100.degree. C. It was believed that the isomerizations are initiated by protons produced by the water-sulfur dioxide system. None of the methods mentioned are specific for obtaining regioselective isomers from a particular class of olefins and they do not involve particular tertiary carbon atoms.